Two-cycle engine



Aug. 29,1933.

F. SHOEMAKER TWO-CYCLE ENGINE Filed 19915,A e, 1951 2 "Sheetsfsneet 1 Patented Aug. 29, 1933 UNITED STATES PAfrEN'i OFFICE to General Motors Detroit. Mich., a corporation ch Corporation, of Delaware Application February 6, 1931. Serial No. 513,850

7 Claims. (Cl. 12S-59) This invention relates to internal combustion engines. Its particular purpose is to increase efficiency and lower fuel consumption.l Accomplishment of this end is had largely by the thorl ough scavenging or discharge of spent gases or products of combustion from the engine cylinder, whereby a minimum dilution of the fresh charge of gases occurs, and also by the complete filling and uniform distribution of fresh gases throughout the combustion chamber and cylinder. The invention may be embodied in the construction of a two-cycle engine substantially as shown in the accompanying drawings, wherein Figure l is a vertical sectional view through one cylinder of an engine assembly.

Figure 2 is a .bottom plan view, partly in section, of the removable head shown in Figure 1. Figure 3 is a fragmentary sectional view of one form of valve control mechanism, and

Figure 4 is a section taken on line 4-4 of `Figure 3. 4

Referring to the drawings, the reference numeral 1 indicates a water jacketed cylinder block and 2 is a piston reciprocable in the cylinder bore and connected in the usual fashion with the engine crankshaft. In the wall of the cylinder there are shown two'ports or passages 3 which are adapted to be uncovered by the piston in the lower or outer limit of piston movement for the escape of exhaust gases from the cylinder.; Removably secured to the cylinder block isa jacket head 4 having about each cylinder and in lineI with the axis of the cylinder bore, a dome or substantially spherical shaped combustion space or chamber 5 which is provided with a restricted neck 6 and a conical or flaring mouth I leading into the cylinder, the side wall tapering from the restricted neck portion to the interior surface of the cylinder bore. The head shown in Figure 3 is intended for a four cylinder engine,

, as will be obvious since there are provided 'fourv of such combustion domes, one for each cylinder, it being understood, however, that the number of cylinders is immaterial to the present invention. Leading into the dome 5 from opposite sides are a pair of inlet ports or passages 8-8 disposed laterally and at an angle substantially .90 from the axis of the cylinder and offset with respect to each other on opposite sides of the axis, whereby each enters, more or less tangentially, the combustion space. Each inlet port is shown as being controlled by a'rotary valve element 9 rotatably mounted in a cylindrical portion of thel head and provided with an opening 10 through its wall which communicates the interior of the loads this pressure difference is very small and valve element 9 with the inlet port 8 once for each rotation of the valve. The valves may be operated by any suitable mechanism in predetermined timed relation with the rotation of the engine crankshaft. Received within a diagonally disposed opening 11 in the head 4 is an ignition device or spark plug 12 so arranged that its spark-- ingA points extend into the combustion space and are positioned substantially on thecenter line of the cylinder bore and dome.

If desired the arrangement shown in Figures 3 and 4 may be employed to control the amount ot fuel or fresh gases entering the combustion space. The control consists simply of a tubular member 13 nested or telescopically received within the rotary valve element 9 and having a series of openings 14 in the wall thereof for registry with the valve openings 10. To this tubular member 13 is secured an actuating rod 15 by means of which the same may beslid axially in the valve element to vary the extent of registration of the valve openings 10 and 14 and thereby control the amount of fuel supplied to the combustion space, without affectingythe time or duration of opening and closing of the valve. It may be said that in the conventional two cycle rotary valve engine the amount oi' fuel enteringl the cylinder depends somewhat upon the difference in pressures existing in the cylinder and the hollow valve. `At light hence flow to different cylinders can be disturbed easily by slight restrictions or pulsations in the engines. By reducing the area of valve opening without changing the time interval, as through the use of the sleeve 13, the pressure diiference causing flow can be made much larger than any of the disturbing pressures to insure equal charging ofthe several cylinders .and even firing at light loads.

In the operation of the engine the piston 2 is forced outward in the cylinder upon the firing by the spark plug 12 of a compressed fuel charge and just as in conventional two cycle operation, the piston, as it approaches its outermost limit of movement, uncovers the exhaust ports 3 allow- 100 ing the spent gases to pass out of the cylinder. y As the discharge ports are opened the rotation of the valves 9 brings their openings 10 into registry with the intake ports 8 whereupon a fresh charge of a carbureted fuel mixture passes through the oifset passages 8 and into the combustion chamber. The offsetting of the passages imparts to the incoming air or gases a swirling or rotational movement in the' combustion space somewhat as indicated by the arrows in Figure 2, and i1. addi- 110 tion reduces interference to one stream by the other such as would compact both streams and tend to merge suspended particles or small globof the dome, and the swirling ai!" passed axially' through the restricted throat 6 and expands or moves outwardly by centrifugal force in the ilaring mouth '7, completely filling the entire cylinder and forcing out the spent gases. rotational and axial movement into the cylinder avoids dead spaces containing spent gases or in other words, the so-called boring through" by the incoming fresh air column, and produces instead a more clearly defined stratication across the cylinder with minimum mixing of the fresh and spent gases. There results, therefore, scavenging action and' a complete filling of the combustion space with fresh ,gas for the Vsubsequent compression strogge, as well as a degree oi turbulence and agitation sufcient to keep the liquid particles in suspension and insure uniform mixture throughout and a regular speed of flan-le propagation. Consequently, more eidcient operation is had throughout the Whole speed range and particularly during idling. It has been found that idling can be further improved if theeharge is isolated near one valve as by staggering'the valve operation and/or the positioning of the spark plug to one side oi the center line or in one of the intake passages 8 or some recess projecting from the spherical dome 5.

The invention is not necessarily-limited to an engine using a prepared combustible mixture, and the construction described may be used to advantage as a solid fuel injection engine by the substitution in the spari; plug opening of a fuel injection nozzle, in which event a charge of air would be introduced into the combustion chamber through the rotary valves in lieu of a carbureted mixture and the engine run after the usual fashion of a compression ignition engine.

l claim:

l. A two-cycle internal combustion engine having a cylinder and a piston reciprocable in the cylinder, an outlet ior spent gases adapted to be opened when the piston is toward its outer limit of movement, a combustion chamber at theinner end of said cylinder and an inlet for fresh gases opening into said combustion chamber in odset overlapping relation with the axis thereof to inipart to the incoming gases a rotational )moven ment.

2. A. two-cycle internal combustion engine having a cylinder and a piston reciprocable in the cylinder, an outlet for spent gases adapted to be opened when the piston is toward its outer llimit or movement, and a cylinder head embodying a combustion dome and having a pair of (llamem- The combined.

cally opposed inlet passages opening into Aseid combustion dome in offset overlapping relation to each other, and a substantially tangential inlet for fresh gases at the inner end of the cylinder, whereby the incoming gas stream swirls into the cylinder.

3. An internal combustion engine having a cylinder and a piston reciprocable in the cylinder, an outlet from the cylinder which is opened at the lower limit of piston movement, a closure tion dome located wholly Within the head and provided with a restricted noch and a Llaring ,mouth leading into the cylinder, and an inlet opening directly into the dome in slightly offcenter but overlapping relation with the center L ci the dome.

5. A two-cycle internal combustion engine having a cylinder and a piston reciprocable in the cylinder, an outlet port in the cylinder Wall uncovered by the piston at its lower limit or" move- Ii *i ment, a cylinder head closing the end oi the cyl-- inder embodying la dome having a restricted neel: and a flaring mouth leading into the cylinder, and a pair of `inlet passages leading laterally through said head from opposite directions into the dorne in oiset overlapping relation to each other.

6. A two-cycle internal combustion engine hav ing a cylinder and a piston reciprocable in the cylinder, an outlet port in the cylinder Wall adapted to he uncovered by the piston at its outer limit oi movement, a pair of lateral inlet ports oppositely disposed in overlapping offset relation, and valve means for said ports to open the same for at least a portion of the time during which the outlet port is uncovered.

7. A two-cycle internal combustion engine hav-- ing a cylinder and a reciprocatory piston, an outn let from the cylinder adapted to be uncovered by the piston near its outermost limit of movement, a head closing the top ofthe cylinder and ein-l bodying a combustion chamber having a restrict ed neck and a iiaring mouth leading into the cylinder, a pair oi laterally disposed entrance openings on opposite sides of the combustion chamber in overlapping odset relation, and a rotary valve controlling each entrance opening and permitting inow for at least a portion of the time when the outlet is uncovered.

GLEN SHOEMAKER.

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